U.S. Treasury Secretary Jacob Lew on Friday urged Congress to raise the debt limit as soon as possible in order to ensure the government continues to be funded.

The Temporary Debt Limit Extension Act passed by the Congress in February 2014 suspended the statutory debt limit through March 15, 2015. Beginning on March 16, the U.S government's outstanding debt will be at the statutory limit.

If the current suspension is not extended or a higher debt limit not specified in law before March 16, the Treasury will have no room to borrow under standard operating procedures from March 16.

Lew said in a letter sent to the House Speaker that if the cap on borrowing comes into place as scheduled on March 16, the Treasury will have to undertake extraordinary measures to continue to finance the government on a temporary basis.

"Increasing the debt limit does not authorize new spending commitments. It simply allows the government to pay for expenditures Congress has already approved," he said.

Lew said the Treasury would suspend the issuance of the state and local government securities beginning March 13 to avoid running out of room to borrow.

The Congressional Budget Office (CBO) projected this week that the Treasury's extraordinary measures would probably be exhausted and the Treasury would probably run out of cash in October or November.

The debt limit is the maximum amount of debt that the Treasury can issue to the public and to the other federal agencies. The amount of outstanding debt subject to limit has now risen to around 18.1 trillion U.S. dollars, said the CBO.